The present invention relates to a method for proteolytic degradation of fish that uses proteolytic enzyme(s) present in fish muscle to bring about heat-induced myofibrillar degradation, and to produce food products from the autolyzed or hydrolyzed mince.
Declining stocks of fish species has prompted the seafood industry to look for underutilized or untapped fishery resources. Some of the underutilized or untapped commercial fish species that are potential resources are arrowtooth flounder (Atheresthes stomias), yellow fin sole (Limanda aspera), Pacific whiting (Merluccius productus), Peruvian Hake (Merluccius gayi peruanus) and menhaden (Brevoorti tyrannus). These fish species have unacceptable textural attributes due to high levels of proteolytic activity.
Arrowtooth flounder (Atheresthes stomias) is one of Alaska's largest seafood resources. According to a recent estimate of the North-Pacific Fisheries Management Council, the Bering Sea and Gulf of Alaska total allowable biological catch (ABC) for 1992 was 386,180 metric tons (Monsen, M. J. Jr., Alaska Fisheries Development Foundation, Inc. Personal Communication, 1992). The vast arrowtooth resource is presently unmarketable. Presence of proteolytic enzyme (protease) in arrowtooth flounder muscle has frustrated efforts to develop a market for this fish. Protease brings about degradation of myosin during normal cooking that leads to excessive softening of the muscle tissue and results in an unacceptable paste-like texture of the cooked product. Similar enzyme mediated muscle softening has been encountered in Peruvian hake (Niki et al., Bull. Jpn. Soc. Sci. Fish. Vol. 50, No. 11, p. 1917, and Vol. 50, No. 12, p. 2043, 1984), Pacific Whiting (Patashnik et al., Mar. Fish. Rev., Vol. 44, page 1, 1982; Erikson et al., J. Food Sci., Vol. 48, p. 1315, 1983; Kudo et al., Fish Bull. Vol. 85, No. 4, p. 745, 1987), and Yellowfin sole (Konagaya, Bull. Jpn. Soc. Sci. Fish., Vol. 46, No. 8, p. 1019, 1980). The untapped arrowtooth flounder is not utilized due to the present non-availability of technology to manipulate the muscle protease. The stocks are virgin and practically untouched (Anon., Seafood Leader, Vol. 9, No. 5, p. 156, 1989).
Some attempts have been made to produce injected fillet and surimi using protease inhibitory additives. Distribution and diffusion of an inhibitor to enzyme sites present a problem with injection technology. Attempts have been made to produce surimi using sulphydryl blocking agents (Wasson et al., J. Aq. Food Prod. Technol., Vol. 1, No. 3/4, p. 147 and p. 169, 1992). The inhibitor to be used should be a food grade additive certified by regulatory agencies. Surimi technology using chemical additives, if and when available, will utilize less than 20% of the harvested resource (Pedersen et al., Hyperfiltration Technology for the Recovery and Utilization of Protein Materials in Surimi Process Wash Waters, Final Report of Project #NA 8611-H-SK140, Prepared for National Marine Fisheries, Department of Commerce, U.S.A., 1989; Lee, Food Technol., Vol. 40, No. 3, p. 115, 1986). Remainder of the harvest (more than 80%) will be discarded as processing waste. Furthermore, consumers tend to dislike food products manufactured with additives. With a declining market price for surimi, the economic feasibility for commercial production of arrowtooth surimi is doubtful. At the present market value it is not even possible to recover the manufacturing cost.
Utilization of arrowtooth flounder may lead to development of a new fishery with marketing potential of about 386,180 metric tons a year. According to some fisherman of Kodiak, abundance of arrowtooth flounder may be preventing the resurgence of shrimp fisheries in the Gulf of Alaska. Utilization of arrowtooth flounder may help revive shrimp and other crustacean species.
Development of a new technology for utilization of arrowtooth flounder will lead to development of a new fishery. The process of the present invention will utilize a vast supply of valuable proteins and produce consumable products.